Cable ties are in widespread use in bundling together electrical wires to form harnesses in motor vehicles and the like. The majority of cable ties are a one piece construction that is molded of a nylon polyamide plastic such as the cable ties disclosed in U.S. Pat. Nos. 3,542,321 and 3,872,547. These cable ties have a head and a strap extending from the head which is wrapped around a bundle of wires and then inserted through the head whereupon a pawl in the head engages teeth on the strap. The strap is pulled tight around the wire bundle, for example by a tool like that illustrated in U.S. Pat. No. 3,661,187, which cuts off the excess cable strap after tightening the strap around the wire bundle. The engagement of the pawl in the head with the teeth on the strap retains the cable tie in the tensioned condition around the cable bundle. In production it has been found difficult to mold such cable ties so that the engagement between the pawl and the strap reliably provides a sufficiently high force resisting pull out of the strap from the head.
It has long been realized that a much higher resistance to pull out force can be obtained by utilizing a metal pawl in the head to engage the plastic strap, as in the cable tie of U.S. Pat. No. 3,588,961. Production of such ties is, however, more expensive.
With both the all plastic cable ties and the cable ties with a metal pawl of the prior art, the cable tie strap is of a specified length and the excess length of cable strap which is threaded through the head is cut off and thrown away. Typically, several cable ties are produced with varying length straps to accommodate various diameters of wire bundles. While the desirability of using only the needed amount of strap material has been recognized in U.S. Pat. No. 3,353,227, the system of that patent is undesirably complex.